The present invention relates to a panel for displaying messages, of the type comprising a plurality of light emitting elements arranged in matrix form on a display surface.
It relates more particularly to a panel for displaying variable messages, used for road or motorway signs.
Such messages must be able to be read by the road users from afar. The light emitting elements must therefore emit a light beam of high intensity in a direction opposing the axis of the traffic. In addition, the distances between two consecutive emitting elements must be relatively small, for the user to have the impression of seeing a continuous image, although this is made in the form of light spots.
Light emitters generally comprise lamps or electroluminescent diodes which emit a light beam having an apex angle clearly greater than the angle of the beam strictly necessary for the sign.
In order to obtain the desired light intensity, these light emitters consume clearly more energy than the useful quantity of light, which brings about problems of cooling the panel supporting the light emitters.
In order to increase the output of the light emitters, parabolic reflectors may be used, which reflect the light beam emitted by the light emitter in a narrower pencil, the light emitter being placed at the focus of the reflector. However, the presence of these reflectors notably increases the distance between two light emitters, which is detrimental to the legibility of the message.
It is an object of the present invention to overcome these drawbacks.
The invention achieves this object in that each light emitting element is constituted by a first end face of an oblong body made of a transparent material and which comprises on its second end face at least one cylindrical housing in which a light emitting source is placed, said housing presenting a bottom having a convex internal surface so as to concentrate the light flow emitted by said source and illuminating said bottom, into a narrower beam directed towards the first end face, said bodies being disposed in rows and columns and separated from one another.
The light emitting source is advantageously an electroluminescent diode.
The body preferably presents a quadrangular section along a transverse plane.
To allow mixing of the lights emitted by a plurality of light sources emitting in the same ranges of colors or different ranges, the body comprises, on its second end face, three separate cylindrical housings each receiving a light emitting source. Two housings are provided laterally near an edge of the second end face and the third housing is provided in the median zone of the opposite edge.
In order to improve the light output, the body presents an annular swelling defined on each lateral face of the body by two planar surfaces which intersect in a transverse plane lying between the bottom and the first end face, said surfaces being intended to reflect at least a part of the light rays illuminating the cylindrical wall of a housing towards the first end face.
In order to allow fixation of the body in an orifice of a support, the body presents studs near its first end face.